DEVELOPMENT OF NERVES CONTAINING NITRIC-OXIDE SYNTHASE IN THE HUMAN MALE UROGENITAL ORGANS

Objective To determine the spatial and temporal distribution of nitric oxide synthase (NOS) in the urogenital organs of a series of human ma le fetuses, using an immunohistochemical technique. Material and metho ds Thirteen pre-natal specimens ranging in gestational age from 13 to 30 weeks were acquired following abortion or miscarriage. The distribu tion of NOS, which catalyses the production of nitric oxide (NO), was revealed using an indirect immunolabelling technique and compared with the overall innervation of each specimen visualized using the general nerve-marker protein gene product 9.5 (PGP). Results At 13 weeks of g estation the majority of nerves supplying the developing prostate glan d expressed NOS while similar nerves formed a very minor proportion of the total innervation to the urinary bladder and intramural ureters, With increasing gestational age, NOS-containing nerves became more num erous in the lower urinary tract, the majority occurring at the bladde r neck and around the prostatic urethra. In contrast, NOS-containing n erves were not detected in the muscle coat of the vas deferens and sem inal vesicle until 23 weeks of gestation and at 30 weeks still only fo rmed a small proportion of the intramuscular nerves, From 23 weeks onw ards NOS-containing nerves were present occasionally in the dense sube pithelial nerve plexuses which developed in the bladder, prostate, vas deferens and seminal vesicle, Also from 23 weeks onwards, many of the epithelial cells lining the vas deferens, seminal vesicle and ejacula tory ducts showed immunoreactivity to NOS but no immunoreactivity was observed in the epithelial lining of the urinary bladder and the intra mural ureters. Conclusion Based on the comparative density of NOS-cont aining nerves and the difference in their temporal development among t he various urogenital organs it is apparent that NO plays an increasin gly important role in the autonomic control of the lower urinary tract during fetal development but that its involvement in the functional c ontrol of the vas deferens and seminal vesicle is relatively minor bef ore birth.